Estimation of Dry Deposition of Atmospheric Mercury in Nevada by Direct and Indirect Methods

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• 作者：Seth N. Lyman ; Mae Sexauer Gustin ; Eric M. Prestbo ; Frank J. Marsik
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：March 15, 2007
• 年：2007
• 卷：41
• 期：6
• 页码：1970 - 1976
• 全文大小：259K
• 年卷期：v.41,no.6(March 15, 2007)
• ISSN：1520-5851

文摘

Atmospheric models and limited measurements indicatethat dry deposition of atmospheric mercury is an importantprocess by which mercury is input to ecosystems. Tobegin to fill the measurement data gap, multiple methodswere used simultaneously during seasonal campaignsconducted in 2005 and 2006 to estimate dry deposition ofatmospheric mercury at two Mercury Deposition Network(MDN) sites in rural Nevada and in Reno, Nevada.Gaseous elemental mercury (Hg⁰), reactive gaseousmercury (RGM), and particulate-bound mercury (Hg_p)concentrations were measured using Tekran 2537A/1130/1135 systems. These speciated measurements were combinedwith on-site meteorological measurements to estimatedepositional fluxes of RGM and Hg_p using dry depositionmodels. Modeled fluxes were compared with more directmeasurements obtained using polysulfone cation-exchange membranes and foliar surfaces. Dynamic fluxchambers were used to measure soil mercury exchange.RGM concentrations were higher during warmer months atall sites, leading to seasonal variation in the modeledimportance of RGM as a component of total depositionalload. The ratio of dry to wet deposition was between 10 and90%, and varied with season and with the methods usedfor dry deposition approximations. This work illustrates thevariability of mercury dry deposition with location andtime and highlights the need for direct dry depositionmeasurements.